..g is one of the most heritable behavioural traits, and genes that contribute to the heritability of g will certainly be identified. What are the scientific and social implications of finding genes associated with g?..

..The seven papers in this special section chart where we are in the quest for quantitative trait loci (QTLs) in key areas of child psychology and psychiatry such as reading and hyperactivity. But we are not there yet...

Why are children in the same family so different? Nonshared environment a decade later

..Instead we are using the same design to screen markers such as cSNPs and SNPs in regulatory regions that are likely to include functional polymorphisms in which the marker can be presumed to be the QTL...

Generalist genes and learning disabilities

Robert PlominSocial, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King s College London, London, United KingdomPsychol Bull 131:592-617. 2005

..Third, genes that affect one learning disability are also likely to affect other learning disabilities. These quantitative genetic findings have far-reaching implications for molecular genetics and neuroscience as well as psychology...

DNA

R PlominGenetic and Developmental Psychiatry Research Centre, King s College London, United KingdomPsychol Bull 126:806-28. 2000

..Finally, the authors discuss behavioral genomics and predict that DNA will revolutionize psychological research and treatment early in the 21st century...

..11 (P < 0.00000003) with g. This shows that future SNP sets that will incorporate many more SNPs could be useful for predicting genetic risk and for investigating functional systems of effects from genes to brain to behavior...

..The present SNP strategy combined with DNA pooling and large samples represents a step towards identifying QTLs of small effect size associated with complex traits in the postgenomic era when all functional polymorphisms will be known...

GENESiS: creating a composite index of the vulnerability to anxiety and depression in a community-based sample of siblings

..Although replication is necessary, these results suggest that the genetic etiology of low g during infancy and early childhood is at least as great as the heritability of g in the unselected population...

Genetic and environmental origins of verbal and performance components of cognitive delay in 2-year-olds

..Similar estimates were found for unselected individual differences and selected extreme groups. A framework is proposed that focuses on quantifying the etiologies of disorders (QED) as measured on continuous dimensions...

..These data suggest that higher SSADH activity is associated with higher intelligence across the general population. The effect is small, with each allele having an effect size translating to about 1.5 IQ points...

DNA by mail: an inexpensive and noninvasive method for collecting DNA samples from widely dispersed populations

..The purpose of this paper is to recommend this technique to the behavioral genetics community and to present results of our use of this technique to obtain DNA by mail for 114 2-year-olds and 116 adults...

Genetic contributions to continuity, change, and co-occurrence of antisocial and depressive symptoms in adolescence

..We conclude that QTL effect sizes, even for highly heritable common disorders and quantitative traits such as early reading disability and ability, might be much smaller than previously considered...

..Although the power of the sibling data is low, the combined findings from the two designs suggest that genetic effects on depressive symptoms in childhood may be somewhat smaller than previously estimated in twin studies...

..02). These results indicate that 37% of the twin-estimated heritability (30/82%) can be explained by additive effects of multiple common SNPs, and provide compelling evidence for strong genetic influence on adiposity in childhood. ..

Visual analysis of geocoded twin data puts nature and nurture on the map

..Evidence of increasing heritability of BMI over childhood can seem paradoxical given longer exposure to environmental influences. Genomic data were used to provide direct evidence of developmental increases in genetic influence...

..There are now some opportunities for direct translational research but there is a much greater need for hypothesis-based bridging studies that occupy a crucial mid-phase in the pathway from science findings to health benefits...

..This study takes an individual differences approach to determine the degree of phenotypic and aetiological overlap between autistic traits and ADHD behaviours in the general population...

Heritability of antisocial behaviour at 9: do callous-unemotional traits matter?

Essi VidingDepartment of Psychology, University College London, and SGDP Centre, Institute of Psychiatry, King s College London, London, UKDev Sci 11:17-22. 2008

..The heritability difference was even more pronounced in magnitude when hyperactive symptoms were controlled. CU traits thus appear to index one valid way of sub-typing children with early-onset AB...

Reading exposure: a (largely) environmental risk factor with environmentally-mediated effects on reading performance in the primary school years

..72 heritability and 0.10 shared environment). The strong genetic component, which this study confirms, is not unitary but distributes differently across the phenotypic aspects of otitis media and probably across pathogenetic stage...

Twins early development study (TEDS): a multivariate, longitudinal genetic investigation of language, cognition and behavior problems in childhood

..We found weak evidence for association with COMT genotype, when the females and males were considered separately, and for MAOA genotype in males only. There was no significant interaction between COMT and MAOA...

..49, which is significantly greater than heritability for the rest of the population in early childhood. These results suggest that mild mental impairment is a good target for neuroscience research on global brain function and dysfunction...

Outcomes of early language delay: I. Predicting persistent and transient language difficulties at 3 and 4 years

..This finding held even when we excluded those children with language impairment whose nonverbal score indicated general cognitive delay. These results point to a general genetic factor that includes both language and nonverbal problems...

..Although each SNP accounts for a small amount of variance, their effects are additive and they can be combined in a 'SNP set' that can be used as a genetic risk index for MMI in behavioral genomic analyses...

..64 and shared environment correlation of 1.00. We conclude that to a large extent, the same genetic and environmental factors underlie the development of individual differences in a wide range of linguistic skills...

Genetic heterogeneity between the three components of the autism spectrum: a twin study

Research Grants2

..Identifying genes associated with reading disability will eventually lead to better diagnoses, individually tailored treatments, and interventions that can prevent the development of reading disability. ..